The quantum physics of artificial light harvesting

Plants and bacteria make use of sunlight with remarkably high efficiency: nine out of ten absorbed light particles are being put to use in an ordinary bacterium.

Photosynthesis model system

TU Wien

For years, it has been a pressing question of modern research whether or not effects from quantum physics are responsible for this outstanding performance of natural light harvesters. A team of European research groups, a collaboration between universities in Vienna, Ulm, Cartagena, Prague, Berlin and Lund, have examined these quantum effects in an artificial model system.

It was shown that the hotly debated quantum phenomena can be understood as a delicate interplay between vibrations and electrons of the involved molecules. The resulting theoretical model explains the experiments perfectly. The article was published in Nature Communications.

The studied artificial light harvester is a supramolecule, consisting of hundreds of thousands of light absorbing molecules, arranged in close proximity to one another and in an orderly fashion.

Such architecture puts these systems in between noisy living cells and strictly organized quantum experiments at low temperatures: supramolecules are still governed by the same quantum effects as natural photosynthetic systems, but without the noisy background that makes their investigation so difficult in biological systems.

The research team employed polarized light to isolate the desired quantum-dynamical effects. Studying such ordered systems does not only further our understanding of natural photosynthesis, it also helps us to appreciate the physical mechanisms necessary for energy-efficient, cheaper, more flexible and lighter photovoltaic cells.

Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.

It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:

The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.

One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...